Double lock stitch sewing machines



NOV. 28, 1967 A, KENNEDY ET AL 3,354,852

DOUBLE LOCK STITCH SEWING MACHINES Filed April 16, 1965 7 l5Sheets-Sheet l A. M. KENNEDY ET L I DOUBLE LOCK STITCH SEWING MACHINESFiled April 16, 1965 Nov. 28, 1967 15 SheetS- Sheet 2 NOV. 28, 1967 N YET AL 3,354,852

DOUBLE LOCK STITCH SEWING MACHINES Filed April 16, 1965 15 Sheets-Sheet3 Nov. 28, v1967 A. M. KENNEDY ETAL 3,354,852

DOUBLE LOCK STITCH SEWING MACHINES l3 Sheets-Sheet 4 Filed April 16,1965 A. M. KENNEDY ET AL DOUBLE LOCK STITCH SEWING MACHINES Nov. 28,1967 13 Sheets-Sheet 5 Filed April 16. 1965 1967 A. M. KENNEDY ETAL3,354,852

DOUBLE LOCK STITCH SEWING MACHINES Filed April 16, 1965 13 Sheets-Sheet6 Nov. 28, 1967 KENNEDY ETAL 3,354,852-

DOUBLE LOCK STITCH SEWING MACHINES l3 Sheets-Sheet 7 Filed April 16,1965 FIGIO Nov. 28, 1967 A. M. KENNEDY ET AL 3,354,852

DOUBLE LOCK STITCH SEWING MACHINES Filed April 16, 1965 13 Sheets-Sheet8 Nov. 28, 1967 A. M. KENNEDY ETAL 3,

DOUBLE LOCK STITCH SEWING MACHINES Filed April 16, 1965 v1s Sheets-Sheet9 A. M. KENNEDY ET 3,354,352 DOUBLE LOCK STITCH SEWING MACHINES Nov. 28,1967 l3 Sheets-Sheet l 0 Filed April 16, 1965 Nov. 28, 1967 KENNEDY ETALDOUBLE LOCK STITCH sra 15 Sheets-Sheet 11 Filed April 16, 1965 Nov. 28,1967 A. M. KENNEDY ET AL 3,354,852

DOUBLE LOCK STITCH SEWING MACHINES Filed April 16, 1965 13 Sheets-Sheet12 Filed April 16, 1965 A. M. KENNEDY ET AL DOUBLE LOCK STITCH SEWINGMACHINES l5 Sheets-Sheet 13 SE 9 U.

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United States Patent DOUBLE LOCK STITCH SEWING MACHINES Alan MalcoimKennedy, Collaroy Plateau, New South Wales, and Keith Samuel Wood,Chester Hill, New South Wales, Australia, assignors to Bonds-Wear Pty.Limited, Camperdown, near Sydney, New South Wales, Australia Filed Apr.16, 1965, Ser. No. 448,592

Claims priority, application Australia, Apr. 24, 1964,

Claims. (Cl. 112--252) ABSTRACT OF THE DISCLOSURE Means incorporated ina 400 type double lock stitch sewing machine which permits an operatorto sever, at the completion of a sewing operation, all sewing threadsattached to a sewn article, such as a garment, so that the seam or hemdoes not require further trimming.

This invention relates to double lock stitch sewing machines which makea stitch known as a 400 type stitch. The invention has been devised toprovide means to be incorporated in the machine whereby an operator cansever all sewing threads attached to a sewn article, a garment forexample, at the completion of a sewing operation so that the seam or hemso made does not require further trimming.

The means of this invention comprise co-acting components, namely:

(i) A presser foot incorporating wiping, holding and cutting blade unitsmounted on the presser bar of a machine to hold the needle and coverthreads and to sever such threads at the completion of a sewingoperation adjacent the garment being sewn and to hold the free ends ofthe threads until they are pulled into the next garment to be sewn.

(ii) A second thread cutting unit mounted On the machine below andjuxtaposed the throat plate and including a loop, thread slackener and apick-up finger;

(iii) Slackeners for the needle and cover threads to minimise thelikelihood of breaking such threads at the commencement of a sewingoperation; and

(iv) Means to actuate the components (i), (ii), (iii).

One embodiment of the invention is illustrated in the accompanyingdrawings as applied to a three needle sewing machine. It is to beunderstood that the invention can be applied to sewing machines of thetype referred to, having one or any number of needles.

FIGURE 1 is a front elevation in perspective of a sewing machineincorporating the invention.

FIGURE 2 is a rear elevation in perspective of the same machine showingcam actuating mechanism for the components (i), (ii) and (iii).

FIGURE 3 is a schematic perspective view of the thread tension releasemechanism, other mechanism being omitted for clarity.

FIGURE 4 is a fragmentary section on the line 4-4 of FIGURE 3;

FIGURE 5 is a schematic view mainly of the foot lifting mechanism;

FIGURE 6 is a fragmentary section on the line 6-6 in FIGURE 5;

FIGURE 7 is a schematic view of the pick-up finger mechanism associatedwith the second thread cutting unit;

FIGURE 8 is a schematic view of the actuating mechanism for the cuttingand the wiping and holding blades;

FIGURE 9 is an exploded perspective view of the presser foot and of thecutting and the wiping and holding blades incorporated therein;

FIGURE 10 is an enlarged perspective view of the presser foot with themechanism of FIGURE 9 in the normal at rest position;

FIGURE 11 is a similar view to FIGURE 10 showing the mechanism inposition to cut the needle and cover threads;

FIGURE 12 is a fragmentary perspective view of the lower cuttermechanism, positioned below the foot, in its normal at rest position,also showing the looper thread slackener;

FIGURE 13 is a similar view to FIGURE 12 showing the lower cuttermechanism in position to cut the threads, also showing the looper threadslackened;

FIGURE 14 is a schematic view of the looper thread slackener and itsactuating mechanism;

FIGURE 15 is an elevation in perspective of the sewing machine whereinthe components (i), (ii) and (iii) are actuated by pneumatic units;

FIGURE 16 is an enlarged rear elevation in perspective showing two ofthe pneumatic units used to actuate the thread cutting mechanisms;

FIGURE 17 is fragmentary perspective view on an enlarged scale, of amodified form of component (iii), in the at rest position; and

FIGURE 18 is a similar view to FIGURE 17 showing the lower cuttingmechanism in a position to cut the threads.

The presser foot 1 is a rectangular plate having an upturned end 2 atthe front and raised side portions 3 and a bracket 4 at the rearthereof. There is a slot 5 through the plate for the passage of needles6 and threads 7-151, and a second slot 8 through the upturned end 2 ofthe presser foot, provides clearance for a wiping blade. The raised sideportions 3 form slide guides for a wiping unit 9 which includes a wipingblade 10 adapted to travel across the needle slot 5. The unit 9 alsoincorporates a lost motion slot 13 in the edge thereof remote from thewiping blade 10 and a post 14. A bellcrank fulcrumed to post 56, haspins 57 on one limb projected on each side of the post 14 and its otherlimb is connected by rod 59 to actuating means to be described.

The cutter blade is in the form of a lever 17 mounted on a fulcrum pin12 fixed in the presser foot 1 beneath the unit 9 and it is adapted totravel in shear across the needle slot 5. It is so moved by a pin 18 onthe power end thereof which pin projects into the lost motion slot 13. Acover plate 20' fixed to the presser foot 1 above the unit 9, has aguide and travel limit slot 19 therein for the post 14. Movement oflever 17 is effected by contact of pin 18 with the ends of the lostmotion slot 13 upon reciprocation of the unit 9.

Adjacent the upturned end 2 of the presser foot 1, a journal pin 21 ismounted in a bracket 22 over the path of the wiping blade 10. A holdingblade 23 has a boss 24 thereon whereby it is rotatably mounted on thejournal pin 21. A torsion spring 26 on the journal pin 21 acts on theholding blade 23 to hold it in engagement with the presser foot inposition to resiliently register with the wiping blade 10 when thelatter is moved to thread drawing position.

The sequence of movements of the wiping, holding and cutting componentson the presser foot 1 is that the wiping blade 10 and the cutting blade17 are in the retracted position during a sewing operation. At thecompletion of such an operation they are moved in sequence by means tobe described, across the needle slot 5. The wiping blade 10 carries withit the bight of the needle and cover threads 7-151 under the holdingblade 23. On further movement of the wiping blade 10, the pin 18 on thecutting blade 17 is engaged by the adjacent end Wall of the lost motionslot 13 and is moved across the needle slot 5, thus severing the threads7-151 which are still 3 gripped between the wiping blade and the holdingblade 23.

Consequently, at the commencement of the next sewing operation there isno likelihood of the threads 7 being pulled out of the needles. Theholding blade 23 ensures that the ends of the threads are held inadvance of the next sewing cycle and in a position to be concealed bythe stitching of the next sewing cycle and are therefore not loose. Thenext sewing operation cannot be commenced until the wiping blade 10 andthe cutting blade 17, are moved to their respective retracted at restpositions. As the wiping blade 10 is moved towards retracted position byits actuating mechanism, the other end wall of the lost motion slotengages the pin 18 and simultaneously moves the cutting blade to itsretracted position. The ends of the threads 74.51 are lightly held bythe holding blade 23 and consequently they are drawn into the stitchingof the next sewing cycle.

The bracket 4 incorporates a clamping socket 27 whereby the presser foot1 is mounted on the presser bar 28 of the machine. In effect, thepresser foot 1 above described replaces the conventional presser footand is located in the same position relative to the machine throat plate29 by the means normally incorporated for raising and lowering theconventional presser foot.

The second thread cutting unit comprises a cutting blade and a pick-upfinger to carry the looper thread to a position where it is severed bythe cutting blade. The cutting blade 30-, FIGURES 12, 13 is fixed on ashaft 31 in a position where it can be moved in shear with the side ofthe throat plate 29. The shaft 31 is supported in a bearing bracket 32on a base plate 33 on the machine. The cutting blade 30 is held inshearing engagement by a spring 33a. It is moved in a cutting operationby a bent crank 34 which is connected by an arm 35 to a reciproeatingrod 36. The cutting blade 36 is moved to retracted position by a spring37 connected to the bent crank 34 and to the base plate 33. Thereciprocating rod 36 also has fixed to it, a hook 38 which is located topull the looper thread 39 through the looper thread part of standardneedle and looper thread tension assembly 40, FIG- URE 1 to providesuificient looper thread 39 beyond the cutting position, so that oncommencement of the next sewing operation the looper thread 39 is notpulled out of the looper 41, FIGURES 12, 13. The rod 36 is reciprocatedby one limb of a bellcrank 42 fulcrumed on the base plate 33. The otherlimb of the bellcrank 42 is connected by a rod 43 to actuating mechanismto be described.

The pick-up finger 44 of the second thread cutting unit is mounted on apost 45 and this post 45 is fixed to a reciprocating rod 46 mounted inbearings 47-48 on the machine. The rod 46 is connected to a crosshead 49and a lever 50 fulcrumed as at 51 has its work end slidably locatedbetween pins 52 on the crosshead 49. The power end of the lever 50 isconnected by links 53 to a push rod 54 which in turn is connected toactuating means to be described.

The next component is the needle thread slackener, the function of whichis to provide sufiicient slack for the needle threads 7, between thetensioner assembly 40 and the needles 6, to minimize the likelihood ofbreaking the threads 7 by excess strain at the commencement of a sewingoperation. The needle thread slackener comprises a lever fulcrumed inbracket 61 on the top of the machine. The power end of the lever 60 isactuated by a push rod 62 which is in turn actuated by a foot liftbellcrank 63 through a connecting rod 64 which rod 64 is adapted to beactuated by means to be described. The work end of the lever 60 is inregister with a rod 65 which is slidable vertically in guides 66 on theface of the machine and held in upper position by a spring 67. This rod65 has a crosshead 68 on it and an arm 69 on the crosshead engages theneedle threads 7 between the tensioning device 40 and the conventionaltake-up thread carrier 70. Downward movement of the crosshead 68 and thearm 69 which is in engagement with the needle threads 7 draws suchthreads through the tensioners 40 in a slackening operation.

One form of means to actuate the components (i), (ii) and (iii) throughrods 59, 64 and 43-54, FIGURES 1-13, consist of cams 71, 72, 73 and 74on shaft 75 mounted in a bracket assembly 76 mounted on the machine. Theshaft 75 has a pulley wheel '77 thereon and a chain or cable 78, havingat least one turn on the pulley 7'7 and anchored at one end thereto, hasits other end connected to the plunger 73a of a pneumatic cylinder 78bactuated by a foot pedal lever 79. The cylinder 78b when energized willrotate the pulley wheel 77 and cam shaft 75 approximately through 270degrees and a clock type torsion spring 75a will return the shaft 75 toits initial position when the cylinder 78b is deenergized. A collar 80free on the shaft 75, has a bent arm 81 thereon which is adapted to abuta stop 82 on the bracket 76 and a carrier 83 on the cam 74 and limit theturning movement of the shaft 75 in one direction. A striker 84, alsofixed on the cam 74 is adapted to abut the opposite edge of the bent arm81 on reverse movement of the shaft 75 and in this movement the bent arm81 actuates the thread slackener in a manner to be described. Thedistance between the carrier 83 and the striker 84 provides a period oflost motion in the actuation of the thread slackener, which brings thisaction into the sequence of operation of the other components.

The rod 59, which actuates the wiping and holding blade 16, is connectedto one end of a bent cam follower arm 85 which has a bearing 86 on itsother end whereby it is supported on a journal pin 87. It has a camfollower 88 projected into a cam groove 89 in the cam wheel 73.

The rod 64, which actuates the needle thread slackener, is connected toa crank 90 on a shaft 91 and the shaft 91 has an arm 92 connectedthereto. The arm 92 is connected by links 93, 94 and 95 to an arm 96rotatably mounted on journal pin 87. The link 94 has an extension in theform of a bearing 97 which is mounted on the camshaft 75. The arm 96 hasa cam follower 98 adapted to register with the cam 74. The cam 74 isadapted to move the arm 92 downwardly through the described linkage,against the action of a retracting spring (not shown), and the bent arm81 is moved by the striker 84 to contact the link 94 and hold the arm 92in the down position to which it has been moved by the cam 74, for thetimed operating sequence.

The rod 43 has an arm 99 fixed on its end and fixed to a rotatablemember 100 on the journal pin 87. The rotatable member 100 has a crank101 thereon and a cam follower 102 on the crank 101 is adapted to beengaged 'by the cam 71. A stop 103 limits throw-out movement. The rod 54has a crosshead 104 fixed thereon and a cam follower rod 105 pivoted tothe crosshead 104 is fixed to shaft 106 rotatable in bearings in thebracket assembly 76. A cam follower 106:: on the rod 105 projects into acam groove 107 in the cam wheel 73. The cam groove 107 is a continuationof the cam groove 89.

When the threads are to be cut, the lever 60 must be depressed a shortdistance as indicated in FIGURE 3, without lifting the presser foot 1,so that thread tension can be released at the conventional tensioners40. The initial 90 degrees of movement of the cam shaft 75 causes thelever 96 to be forced downwardly to the position shown in FIGURE 4 andwith it the arm 92. The striker 84 secured to the side of the cam 73then engages the side of bent arm 81 and after a further degrees ofmovement the bent arm 81 will be forced into contact with the link 94forcing it down so that the arm 96 and the cam follower 98 leave thesurface of the cam 74 as shown in FIGURE 6. This forces the arm 92 fullydown to the position shown in FIGURE 5 thus lifting the presser foot asshown also in FIGURE 5. This movement occurs after the threads have beensevered by the mechanism previously described.

Like the needle threads 7, the cover thread 151 passes through aconventional first tensioner 152. This tensioner 152 is opened duringthe first depression of the lever 60, to release the tension on thecover thread by the wedge end of arm 153. This arm 153 is slotted as at154 and is slidably mounted on the machine by journal screw 155. The end156 of this arm is held by a spring (not shown) in abutment with arocker arm 157 pivotally mounted on the machine. A pin 158 on the rockerarm 157 is entered into an arcuate slot 159 in a bracket 160 on the arm92 or 92a and the arm 153 is actuated in timed sequence to open thetensioner 152 by the actuating means for the arms 92, 92a previouslydescribed.

Like the needle threads 7, which are held by the wiping blade andholding blade 23 for cutting, the cover thread 151 must also be held forthe cutting operation. For this purpose a conventional second tensioner161 is mounted on the machine. It is normally held open to permit freepassage of the cove-r thread 151 during a sewing operation, by a wedge162 on an extension 163- of the rod 65. Again, during the firstdepression of the lever 60, the wedge 162 is moved clear of thetensioner 161 and the cover thread 151 is held thereby for the cuttingoperation.

It will be seen that the needles 6 must be in the fully raised positionbefore any thread cutting can take place. A sensing device and quickstop motor is known standard equipment on this type of sewing machineand they normally act so as to halt the machine with the needles 6 fullyraised. In case this known mechanism fails an additional safety deviceis fitted as indicated at 108.

This comprises a pin 109 vertically slidable in a slotted guide 110'below the main drive shaft 111 of the machine. One end 112 of a lever113 is entered into a slot in the pin 109 and the other end 114 of thelever is connected to the free end of the lever 92 by a link 115. Ablind hole indicated at 116 in a wheel fixed on the main drive shaft 11is adapted to register with the pin 109 if the machine stops with theneedles 6 raised. If the cam mechanism is now actuated by the cylinder78b the pin 109 will enter the hole 116 in the Wheel and lock the shaft111 to prevent movement of the needles whilst thread cutting takesplace. If, however, the machine does not stop in the correct positionwith the pin 109 in register with the hole 116, the pin 109 will strikethe surface of the wheel and the arm 92 cannot be drawn down from itsnormal position as shown in FIGURE 2 thus preventing movement of the cammechanism and the components actuated thereby, before any thread cuttingcan take place.

The alternative actuating means illustrated .in FIG- URES to 18 consistof pneumatic cylinders. The presser foot 1 and its thread cuttingmechanism is the same as that previously described. However, a modifiedform of the second thread cutting unit is shown in FIGURES 17 and 18.Either form of the second thread cutting unit could be used with thepneumatic actuating means.

As previously described the thread slackeners, thread cutting andpresser foot lifting operations must occur in a correctly timedsequence. To achieve this sequence of operations the pedal 79 (FIGURE15) is adapted to energise a master timing pneumatic cylinder 117mounted on a horizontal plate 118 secured to the machine bench.

A valve actuator 119 is secured to the plunger of the cylinder 117 bymeans of a crosshead 120. The valve actuator 119 is slidably mounted ona guide rod 122 rigidly secured between space end plates 123. Fourcompressed air control valves 124, 125, 126 and 127 are secured betweenthe end plates 123 and adjacent the guide rod 122. When the cylinder 117is actuated its plunger forces the valve actuator 119 past each valve inturn; the leading edge of the valve actuator 119 opening each valve insequence.

The initial valve 124 supplies air to a lower vertical pneumaticcylinder 128 which is anchored to one extension of the base plate 118.The base of a second vertical pneumatic cylinder 129 is secured to theplunger 130 of the first cylinder 128 so that the two cylinders areaxially in line. The plunger 131 of the second cylinder 129 extendsthrough an aperture in the machine bench top and its upper end ispivotally connected to the end of the presser foot lift arm 92a.Actuation of cylinder 128 via valve 124 causes the lever 92a to bepulled downwardiy the short distance necessary to remove tension fromthe threads without lifting the presser foot 1. When the final valve 127is opened, air is supplied to the cylinder 129, the plunger rod 131 ispulled down to its fullest extent so that the arm 92a is pulled rightdown to lift the presser foot 1.

The intermediate valves 125 and 126 supply air to cylinders 132 and 133,respectively, which are horizontally mounted on an angle bracket 134 onthe rear of the sewing machine in the position occupied by the cammechanism previously described.

The plunger rod 135 of the cylinder 132 is pivotally secured to the bellcrank 55 which actuates the cutting and wiping mechanism in the presserfoot 1.

The plunger rod 136 of the cylinder 133 is pivotally connected to linkbars 137 and 138 which are adapted to actuate the second thread cuttingunit.

In the modified form of the second thread cutting unit, the forked end139 of the bar 138 engages a rod 140 slidably mounted in a guide block141 secured below the throat plate 29. A horizontal pick-up finger 142is secured to the free end of the rod 140 adjacent the needle threads 7and looper thread 39. A horizontal cutter blade 143 is secured to theunderside of the throat plate 29 on the opposite side of the needlethreads -7 to the pick-up finger 142.

The front face of the pick-up finger 142 is provided with a longitudinalthrough slot 144 which may have a V notch 145 therein.

When the cylinder 133 is energized the pick-up finger 142 is forcedacross the thread 39 and picks it up. When the pick-up finger 142reaches the end of its stroke the slot 144 receives the cutter blade 143and the thread 39 is severed.

Before the action just described can take place, however, a loop ofslack must be taken in the looper thread 39. To effect this a pneumaticcylinder 146 is secured to the sewing machine base. The plunger 147 ofthe cylinder 146 is normally held in the retracted position shown inFIGURE 17 by an internal spring (not shown). A pipe 148 which suppliesair to the cylinder 132 controlling the presser foot mechanism, has abranch pipe 149 which delivers air to the cylinder 146 just described.

When the valve 125 delivers air to the cylinder 132 air will besimultaneously delivered to the cylinder 146 so that its plunger,147will be projected as shown in FIGURE 18. A finger 150 secured to the endof the plunger 147 engages the looper thread 39 and slackens it as shownin FIGURE 18. This slackening of the looper thread will take placebefore the thread cutting action as the slackening action is controlledby valve 125 whilst the thread cutting is controlled by valve 126.

When the presser foot 1 is to be lowered to recommence sewingoperations, the pedal 79 is moved in the reverse direction so that themaster cylinder 117 withdraws the valve actuator 119 from the valves127, 126, 125 and 124. The plungers in cylinders 132, 133 and 146 arereturned to their initial positions and the arm 92a is raised so thatthe presser foot 1 will be lowered.

The safety device 108 previously described, is actuated by a link 115asecured to the arm 92a. In this form of safety device, the valves 125,126 can only be opened when the needles 6 are raised, by actuation of asafety valve (not shown), which is opened by downward moveblade unitsmounted on the presser bar of said machine to hold the needle and coverthreads and to sever such threads at the completion of a sewingoperation adjacent the garment being sewn and to hold the free ends ofthe threads until they are pulled into the next garment to be sewn, saidpresser foot comprising a rectangular plate having an upturned end atthe front thereof and raised side portions providing slide guides, abracket at the rear of said presser foot for mounting it on the presserbar, said presser foot also having a slot for the passage of needles andthreads therethrough and a second slot through said upturned end toprovide clearance for said wiping blade unit, said wiping blade unitbeing slidably mounted on the presser foot between the slide guides andincluding a post and a wiping blade adapted to travel across the needleslot, said wiping blade unit having a lost motion slot in the edgethereof remote from the wiping blade, said cutting blade unit comprisinga lever rotatably mounted on the presser foot beneath the wiping unit, apin on the power end of said lever, said pin projecting into said lostmotion slot, a cover plate fixed to the presser foot above the wipingblade unit, said plate having a guide and travel limit slot therein forreceiving said post on the wiping unit, said holding blade unitcomprising a holding blade rotatably mounted on the presser foot in thepath of travel of said wiping blade, a spring engaging said holdingblade to hold it resiliently in engagement with the presser foot inposition to resiliently register with the wiping blade,

(ii) a second thread cutting unit mounted on the machine below andjuxtaposed the throat plate and including a looper thread slackener anda pick-up finger,

(iii) slackeners for the needle and cover threads to minimize thelikelihood of breaking such threads at the commencement of a sewingoperation; and

(iv) means to actuate said wiping, holding and cutting blade units ofsaid presser foot, said second thread cutting unit, and said slackenersfor the needle and cover threads, said means comprising link and levermechanisms operatively connected to each of said wiping, holding andcutting blade units of said presser foot, said second thread cuttingunit, and said slackeners for the needle and cover threads, pneumaticmeans operatively connected to said link and lever mechanisms, and afoot pedal controlling said pneumatic means.

2. Improvements relating to a 400 type double lock stitch sewing machineaccording to claim 1, wherein the second thread cutting unit comprises ashaft rotatably supported on said machine, a cutting blade fixed on saidshaft in a position Where it can be moved in shear with the side of themachine throat plate by rotation of said shaft, a reciprocating rodmounted on said machine, a pick-up finger fixed on said reciprocatingrod in a position where it can be moved to carry a looper thread to theposition to be cut, crank means for rotating the shaft on which thecutting blade is fixed, a second reciprocating rod mounted on saidmachine, said crank means connected to said shaft and to said secondreciprocating rod, said second reciprocating rod having .a hook fixedthereon located to pull the looper thread through the looper thread partof said needle and looper thread tension assembly to provide sufficientlooper thread beyond the cutting position and to prevent said looperthread from being pulled out of said looper.

3. Improvements relating to a 400 type double lock stitch sewing machineaccording to claim 1, wherein the needle thread slackener comprises alever fulcrumed on top of the machine, an arm connected to the work endof said lever, said arm being adapted to engage the needle threadsbetween said needles and looper thread tension assembly and said take-upthread carrier, the power end of said lever being operatively connectedto said actuating means; wherein said cover thread slackener comprisesfirst and second thread tensioners mounted on the machine and one oneach side of the sewing position and means to open and close thetensioners in timed sequence, the first tensioner being closed tomaintain tension on the cover thread during a sewing operation while thesecond tensioner is held open by said means, said first tensioner beingopened by said means to permit slackening of the cover thread at thefinish of said sewing operation, said means simultaneously closing thesecond tensioner to hold to the cover thread for the thread cuttingoperation; opening means for said first thread tensioner, said openingmeans comprising an arm connected to the actuating means for the powerend of the needle thread slackener lever, and opening means for saidsecond thread tensioner, said last-mentioned opening means comprising amember operatively connected to the arm on the work end of said needlethread slackener lever.

4. Improvements relating to a 400 type double lock stitch sewing machinewherein said sewing machine includes a presser bar, a throat plate, aneedle and looper thread tension assembly, a looper, and a take-upthread carrier, said improvements comprising in combination:

(i) a presser foot including Wiping, holding and cutting blade units,mounted on the presser bar of said machine to hoid the needle and coverthreads and to sever such threads at the completion of a sewingoperation adjacent the garment being sewn and to hold the free ends ofthe threads until they are pulled into the next garment to be sewn,

(ii) a second thread cutting unit mounted on said machine below andjuxtaposed the throat plate and including a looper thread slackener anda pick-up finger,

(iii) slackeners for the needle and cover threads to minimise thelikelihood of breaking such threads at the commencement of a sewingoperation; and

(iv) means to actuate said wiping, holding and cutting blade units ofsaid presser foot, said second thread cutting unit, and said slackenersfor the needle and cover threads, said means comprising link and levermechanisms operatively connected to each of said wiping, holding andcutting blade units of said presser foot, said second thread cuttingunit, and said slackeners for the needle and cover threads, camfollowers connected to said link and lever mechanisms, a shaft mountedon the machine, cams mounted on said shaft and engaged by said camfollowers, a pedal on said machine, said shaft connected for rotation inone direction to said pedal and spring means acting on said shaftwhereby it is rotated in the opposite direction.

5. Improvements relating to a 400 type double lock stitch sewing machinewherein said sewing machine includes a presser bar, a throat plate, aneedle and looper thread tension assembly, a looper, and a take-upthread carrier, said improvements comprising in combination:

(i) a presser foot including wiping, holding and cutting blade units,mounted on the presser bar of said machine to hold the needle and coverthreads and to sever s u c h threads at the completion of a sewingoperation adjacent the garment being sewn and to hold the free ends ofthe threads until they are pulled into the next garment to be sewn,

(ii) a second thread cutting unit mounted on said machine below andjuxtaposed the throat plate and including a looper thread slackener anda pick-up finger,

(iii) slackeners for the needle and cover threads to minimize thelikelihood of breaking such threads at the commencement of a sewingoperation; and

eners for the needle and cover threads, pneumatic cylinders operativelyconnected to said link and lever mechanisms and control means comprisingcontrol valves for the cylinders, a pneumatic control valve actuator,and a pedal to activate the control valve actuator.

References Cited UNITED STATES PATENTS l0 (iv) means to actuate saidWiping, holding and cutting 1 2 blade units of said presser foot, saidsecond thread 3139849 6/1964 Cohen et a1 1]2 252 cutting unit, and saidslackeners for the needle and 3234900 2/1966 Harris 112 252 coverthreads, said means comprising link and lever mechanisms operativelyconnected to each of said Wiping, holding and cutting blade units ofsaid presser foot, said second thread cutting unit, and said slack- 15JORDAN FRANKLIN, Primary Examiner.

I. R. BOLER, Assistant Examiner.

1. IMPROVEMENTS RELATING TO A 400 TYPE DOUBLE LOCK STITCH SEWING MACHINEWHEREIN SAID SEWING MACHINE INCLUDES A PRESSER BAR, A THROAT PLATE, ANEEDLE AND LOOPER THREAD TENSION ASSEMBLY, A LOOPER, AND A TAKE-UPTHREAD CARRIER, SAID IMPROVEMENTS COMPRISING IN COMBINATION (I) APRESSER FOOT INCLUDING WIPING, HOLDING AND CUTTING BLADE UNITS MOUNTEDON THE PRESSER BAR OF SAID MACHINE TO HOLD THE NEEDLE AND COVER THREADSAND TO SEVER SUCH THREADS AT THE COMPLETION OF A SEWING OPERATIONADJACENT THE GARMENT BEING SEWN AND TO HOLD THE FREE ENDS OF THE THREADSUNTIL THEY ARE PULLED INTO THE NEXT GARMENT TO BE SEWN, SAID PRESSERFOOT COMPRISING A RECTANGULAR PLATE HAVING AN UPTURNED END AT THE FRONTTHEREOF AND RAISED SIDE PORTIONS PROVIDING SLIDE GUIDES, A BRACKET ATTHE REAR OF SAID PRESSER FOOT FOR MOUNTING IT ON THE PRESSER BAR, SAIDPRESSER FOOT ALSO HAVING A SLOT FOR THE PASSAGE OF NEEDLES AND THREADSTHERETHROUGH AND A SECOND SLOT THROUGH SAID UPTURNED END TO PROVIDECLEARANCE FOR SAID WIPING BLADE UNIT, SAID WIPING BLADE UNIT BEINGSLIDABLY MOUNTED ON THE PRESSER FOOT BETWEEN THE SLIDE GUIDES ANDINCLUDING A POST AND A WIPING BLADE ADAPTED TO TRAVEL ACROSS THE NEEDLESLOT, SAID WIPING BLADE UNIT HAVING A LOST MOTION SLOT IN THE EDGETHEREOF REMOTE FROM THE WIPING BLADE, SAID CUTTING BLADE UNIT COMPRISINGA LEVER ROTATABLY MOUNTED ON THE PRESSER FOOT BENEATTH THE WIPING UNIT,A PIN ON THE POWER END OF SAID LEVER, SAID PIN PROJECTING INTO SAID LOSTMOTION SLOT, A COVER PLATE FIXED TO THE PRESSER FOOT ABOVE THE WIPINGBLADE UNIT, SAID PLATE HAVING A GUIDE AND TRAVEL LIMIT SLOT THEREIN FORRECEIVING SAID POST ON THE WIPING UNIT, SAID HOLDING BLADE UNITCOMPRISING A HOLDING BLADE ROTATABLY MOUNTED ON THE PRESSER FOOT IN THEPATH OF TRAVEL OF SAID WIPING BLADE, A SPRING ENGAGING SAID HOLDINGBLADE TO HOLD IT RESILIENTLY IN ENGAGEMENT WITH THE PRESSER FOOT INPOSITION OF RESILIENTLY REGISTER WITH THE WIPING BLADE, (II) A SECONDTHREAD CUTTING UNIT MOUNTED ON THE MACHINE BELOW AND JUXTAPOSED THETHROAT PLATE AND INCLUDING A LOOPER THREAD SLACKENER AND A PICK-UPFINGER,